Transcript Bacteria - Liberty Hill Junior High

Bacteria
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Bacteria
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Single celled organisms
Prokaryotic cell (1-5 microns)
2 Kingdoms
I. Eubacteria
A. live almost everywhere (fresh water, salt
water, land, human intestine; Escherichia
colei)
B. Cell walls of peptidoglycan
C. Cell membranes (some have a second
membrane that makes them especially
resistant to damage
D. Shape
1. Rod – bacilli (bacillus)
2. Spherical – cocci (coccus)
* staphyl (irregular clusters)- staph
infections
* strepto (bead like chain)- strep throat,
yogurt
* diplo (pairs) – pneumonia, gonorrhea,
meningitis
3. Spiral – spirilla (spirillum)
E. Cell Walls – 2 types
1. Gram + (thick walls; retain violet
color)
2. Gram – (alcohol removes stain /
counter stain appears pink or light
red.
F. Movement (if/how) – flagella, lash or
spiral forward, glide on layer of slimlike
material they secrete
G. Energy
1. Heterotrophs
a. Chemoheterotrophs – take in organic
matter for both energy and carbon
(in competition with humans
for food; food poisoning)
b. Photoheterotrophs – photosynthetic
organisms; also use organic
compounds for carbon
2. Autotrophs
a. Photoautotrophs – CO2 and H20 
carbon compounds and O2 (similar
to green plants)
b. Chemoautotrophs – make organic
carbon molecules from CO2
- Use energy directly from chemical
reactions involving ammonia,
hydrogen sulfide,nitrates, sulfur or iron
- Live deep in the ocean (hydrogen sulfide gas)
H. Releasing Energy
1. Obligate (required) aerobes – constant supply
of oxygen (Mycobacterium tuberculosis)
2. Obligate anaerobes – must live in the absence
of oxygen (Clonstridium botulinum – found in
soil; spoils canned food)
3. Faculative (able to function in different ways)
anaerobes – do not require oxygen but are not
killed by it. E.coli lives anaerobically in the
large intestine and aerobically in sewage or
contaminated water
I. Activities
1. Environment – Nitrogen fixation
(legumes – pod bearing plants)
- Decomposition (recycle essential
elements in organic matter)
2. Food Industry – used in making cheese,
fermented dairy products, sauerkraut and
pickles
3. Other industries – antibiotics, chemicals,
dyes, vitamins and enzymes and a
number of pesticides
4. Genetic engineering
5. Human intestine – bacteria synthesize
several vitamins (Vitamin K); break down
certain foods that otherwise escape
digestion.
J. Pathogens
1. tuberculosis, gonorrhea, syphilis, scarlet fever,
food poisoning, Lyme disease, plaque,
tetanus, typhoid fever and most pneumonia.
2. Produce powerful toxins that interfere with
normal body function
3. Rickettsiae (electron microscope) –
transmitted by fleas, ticks, and lice.
chlamydiase – eye infection (trachoma), STDchlamydria
mycoplasmas – many shapes, no cell walls –
pneumonia (type of)
II. Archaebacteria
A. Methanogens – anerobic,heterotrophs ->
produce methane (CH4). Live in swamps,
mud, guts of cows, humans, termits and other
animals
B. Extreme halophiles (salt lovers) – Great Salt
Lake, Dead sea, salted food (cause spoilage)
C. Thermoacidophiles (heat and acid lovers)60o-80o / pH 2-4; mineral springs, thermal
volcanic vents on ocean floor
D. Growth and Reproduction
1. Asexual Reproduction – Binary Fission
2. Sexual Reproduction – Conjugation
E. Spore Formation – Endospores (DNA
surrounded by a small amount of cytoplasm and
a durable cell wall); The endospore has a thick,
protective coat. Its cytoplasm is dehydrated, and
the cell does not metabolize. Under harsh
conditions, the outer cell may disintegrate, but the
endospore survives all sorts of trauma, including
lack of water and nutrients, extreme heat or cold
and poisons. When the environment becomes
more hospitable, the endospore absorbs water
and resumes growth.
Bacterial Diseases
1) Damage cells and tissue of the infected
organism by breaking down the cell for food
2) Release toxins (poisons) that interferes with
normal body activity
3) Symptoms of infection – fever, high white
blood count
4) Prevention – Vaccine – weakened or killed
pathogens cause body to produce
antibodies
- Antibiotics – block growth and production of
bacteria.
Control
1. Sterilization by heat
2. Disinfectants
Food Storage and Processing
1.
2.
3.
4.
Refrigeration
Proper Cooking  rises temp.  kills bacteria
Canning  high temp.  sterile containers
Chemical Treatments – vinegar, sugar (salted
meats, pickled veg., jam)